Most burglar alarms, whether designed to protect residences, commercial properties, or vehicles, sound a warning device upon intrusion of a burglar or vandal so as to frighten said burglar or vandal away. Such alarms typically include some form of detector to detect any shock, motion, or glass-breakage cause by the burglar's or vandal's entry. However, due to the difficulty of distinguishing break-in and vandal attempts from the sound or shock caused by such environmental factors as passing trucks, thunder, wind, or rain, setting the proper sensitivity of such a detector presents a problem to the installer of the alarm system. If the sensitivity is set too high, environmental factors such as those described above may cause the alarm to trigger falsely (this is called a false alarm). But if the sensitivity is set too low, the detector may not be able to detect the burglar's or vandal's entry (which shall be referred to as a "no-alarm"). The present invention is therefore related to an error-free control circuit to prevent false alarms and no-alarms of an alarm's shock, motion, or glass break detector, and thus ensure the alarm's optimum performance.
For the purpose of clarity, in the rest of this patent application, the words "detector" and "detectors" includes any shock, motion, glass break, microwave, infra-red, or other such detectors. Note that such detectors are available from various sources, and therefore are not parts for which a patent is being sought. The word "violation" shall refer to any break-in or vandalism to some protected premises. The work "burglar" shall refer to any burglar or vandal.
According to the present invention, said error-free control circuit provides the following features:
1. The error-free control circuit causes said alarm to sound a temporary pre-entry warning sound when the detector detects any of the above-described environmental noises which might cause a false alarm. Said environmental noises may be interpreted as entry by a burglar by conventional alarms. Such a pre-warning sound warns the car's owner or the alarm's installer that the detector's sensitivity may be set too high.
2. The error-free control circuit causes said alarm to sound a temporary pre-entry warning sound when the detector detects such sounds as a revving motorcycle engine or accidentally hitting the car when the door of a neighboring car is opened. Such a pre-entry warning sound warns persons that they may cause the alarm to sound if they are not more careful.
3. The error-free control circuit causes said alarm to sound when the detectors detect actual violation by burglars.
4. The error-free control circuit causes said alarm to sound a temporary pre-entry warning sound when the detector detects such sounds as someone tapping on the window glass or moving the car's door latch. Such a pre-entry warning sound warns would-be burglars that the detector is working to detect actual violation attempts
5. The error-free control circuit allows easy installation and setting of the detector's sensitivity by giving the above-mentioned warning signals to indicate sensitivity may be set too high, as well as giving a special short alarm sound to indicate detection of actual violation.